Chip boffins hone silicon-brain interface

First slugs. Then humans

Silicon-Slug Talk

In 1991, Fromhertz and company managed to get a simple electronic/ionic dialog going on between a silicon capacitor and a slug neuron - and when we say simple, we mean very, very simple: An electron-carrying signal was sent from a silicon-based capacitor, through an electrolyte, and across a 5nm cell membrane where it induced an ionic channel in the membrane that caused a replication of the pulse of the trigger signal from the chip.

If that last sentence confused you, don't fret - it's both a complex concept to explain and a gross oversimplification of the methods used. The basic take-away: The chip could talk to the cell, and vice-versa. Not that they could say much. But, hey, you have to crawl before you can walk, right?

Importantly, Fromherz's chip/cell communication could be conducted with no corrosive nor electrochemical damage to either the chip or the cell. However, that slug-neuron success was the only giant step in the development of a chip/cell interface for 17 years. It was only earlier this year that the team managed to pull off essentially the same feat with much smaller and far more delicate mammalian neurons, in this case taken and cultured from those great sacrificers for humanity: lab rats.

Back in 1991, the idea of electronics being able to cause brain-cell activity was unsettling to some observers. Fromherz, in fact, read to the assemble engineers a worried comment from one observer from that time: Now that "a functioning neuro-net can be physically attached to a silicon chip," the observer said, we should explore the "philosophical and spiritual consequences." Fromherz brushed aside such concerns, and the audience chuckled in agreement.

Don't be surprised, though, that when this type of brain/electronic interface becomes more controllable, interconnectable, and manageable - and it most surely will - such concerns will be debated. There will, of course, be those who argue strictly from a religious perspective that there are places that science shouldn't go - the Catholic Pope, for example, recently restated his objection to both stem-cell research and in-vitro fertilization. And there will also be those who fear that electronic control over neurological processes will lead us down a slippery slope towards The Borg.

But there are great benefits to be obtained from chip/cell interactions as well. At tomorrow's IEDM, for example, two papers will be presented that will detail recent neuroprosthetic research.

The first, "Systems Design of a High-Resolution Retinal Prosthesis" by J. Weitland and his crew from the University of Southern California, will explain how they have managed to fit 1000 light-sensing electrodes to be installed in a tiny in-eye device, coupled with an advanced image-processing technology, and powered remotely. Their goal: greatly improved artificial sight for the vision-impaired.

The second, "Microelectronics Meets the Brain: Towards Implantable Neural Communications Interfaces" by Y.-K. Song and his cohorts at Brown University, will discuss "thought-to-action telemetry." At the core of their work is an active sensor that's surgically implantable with one element below the skull and that interfaces with the brain, and another above the skull but below the skin that's able to communicate with telemetric devices. The entire system, according to the paper's authors, will be safe and highly reliable.